Coastal impact resistant fenestrations including corner key with overlap geometry

An impact-resistant fenestration unit comprising:

• a frame assembly comprising a sill, a head jamb, and two opposed side jambs;
• a bottom sash, the bottom sash comprising a bottom rail, a check rail, and two opposed stiles, the bottom sash configured to move within the frame between a closed position where a bottom portion of the bottom sash engages a top of the sill and an open position where the bottom portion of the bottom sash is separated from the top of the sill;
• the bottom sash forming a first lower corner, a second lower corner, a first upper corner, and a second upper corner;
• a first corner key configured to engage the bottom sash at the first lower corner, the first corner key comprising a support arm extending in a first direction onto or into a first stile of the two opposed stiles;
• and
• a first reinforcement member disposed on or within the first stile, the first reinforcement member comprising a first end, a second end, and an overlap tab projecting from the first end of the first reinforcement member, wherein the first end overlaps a portion of the support arm of the first corner key;
• the check rail of the bottom sash comprising a surface defining an exterior window side top corner and an interior window side top corner, wherein a radius of curvature of the interior corner is greater than 0.2 inches;
• wherein the impact-resistant fenestration unit exhibits impact resistance properties satisfying ASTM E1996-17 missile level D;
• and
• wherein the impact-resistant fenestration unit exhibits a U factor of less than or equal to 0.40 BTU/h*ft2*° F.

An impact-resistant fenestration unit comprising:

• a frame assembly comprising a sill, a head jamb, and two opposed side jambs;
• a bottom sash, the bottom sash comprising a bottom rail, a check rail, and two opposed stiles, the bottom sash configured to move within the frame between a closed position where a bottom portion of the bottom sash engages a top of the sill and an open position where the bottom portion of the bottom sash is separated from the top of the sill;
• the bottom sash forming a first lower corner, a second lower corner, a first upper corner, and a second upper corner;
• a first corner key configured to engage the bottom sash at the first lower corner, the first corner key comprising a support arm extending in a first direction onto or into a first stile of the two opposed stiles;
• and
• a first reinforcement member disposed on or within the first stile, the first reinforcement member comprising a first end, a second end, and an overlap tab projecting from the first end of the first reinforcement member, wherein the first end overlaps a portion of the support arm of the first corner key;
• the bottom sash comprising a transparent central area and the top sash comprising a transparent central area, wherein the transparent areas cover a surface area of at least 55% of the overall area defined by an outer perimeter of the frame assembly;
• wherein the impact-resistant fenestration unit exhibits impact resistance properties satisfying ASTM E1996-17 missile level D;
• and
• wherein the impact-resistant fenestration unit exhibits a U factor of less than or equal to 0.40 BTU/h*ft2*° F.